High output loudspeaker

ABSTRACT

A loudspeaker system is provided that includes a speaker enclosure having a first opening and a second opening; a first speaker manifold mounted within the enclosure and including a first back wall, four first side walls, and an open first front side substantially in alignment with the first opening; a second speaker manifold mounted within the enclosure and including a second back wall, four second side walls, and an open second front side substantially in alignment with the second opening; a woofer mounted on a first wall of the first side walls; and an acoustic vent mounted in a second wall among the second side walls.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of co-pending U.S. application Ser.No. 13/731,679 filed on Dec. 31, 2012, which claims priority to U.S.application Ser. No. 12/939,404 filed on Nov. 4, 2010, which claimspriority to U.S. application Ser. No. 11/620,395 filed on Jan. 5, 2007,the disclosures of which are incorporated by reference herein in theirentirety.

BACKGROUND OF THE INVENTION

1. Technical Field

The present disclosure relates to a low-frequency sound reproductionsystem for high power output, and more particularly to a low-frequencysound reproduction system having a manifold, a low frequency speaker,and one or more passive radiators and/or air ports.

2. Discussion of the Related Art

A woofer is a loudspeaker driver that is designed to producelow-frequency sounds, typically from around 40 Hertz up to about a fewthousand hertz. Nearly all woofers are driven by a voice coil in amagnetic field, connected to an amplifier. The voice coil assembly is anelectric motor. When current flows through the voice coil wire, the coilmoves according to Fleming's left hand rule, causing the coil to push orpull like a piston. The voice coil is typically cemented to the back ofthe speaker cone, which creates sound waves as it is pushed back andforth.

A sub-woofer is similar to a woofer, but is dedicated to thereproduction of bass frequencies, typically from about 20 Hz to about200 Hz. Since it is difficult for small loudspeakers to reproducefrequencies below 80 Hz, especially above 100 dB, a loudspeaker intendedspecifically for this task is often used. There is a growing demand forcompact, high-output subwoofer systems for use in both home andprofessional settings.

Many existing designs use horn loading to provide high efficiency andlow distortion, but these systems are typically very large. Shorterhorn-loaded systems such as those described in U.S. Pat. No. 5,898,138detail a method of including multiple drivers, ports or passiveradiators into a single horn throat. However, the very short nature ofthe horn severely restricts the efficiency gain and air loadeffectiveness at low frequencies. To obtain better efficiency and stillkeep a small enclosure size, some designs use a low frequency horn thatis folded. U.S. Pat. No. 4,215,761 relates to a bass sound projectionsystem which uses a folded horn. While this approach reduces the overallsize of the system, it is still very large compared to a conventionalsealed or ported enclosure.

An alternate solution to standard horn loading is called “manifolding”and was proposed in U.S. Pat. No. 4,733,749. This design increasesefficiency and reduces distortion while allowing the use of relativelylarge loudspeakers in a very compact cabinet. This configurationoptionally uses a sealed or ported cabinet, and the manifold may formthe throat of a horn for even higher performance at the cost ofincreased size.

Other designs employ multiple chambers in various styles of bandpassenclosures. These systems can vary in size significantly, but thesmaller designs are usually designed to have high mid-bass efficiency(50-150 Hz) and sacrifice low frequency extension. Most commercialapplications also have a severely degraded transient response as anatural result of high-order upper and lower frequency rolloffs.

Alternate designs use passive radiators (drones) in place of ports as amethod to decrease system size and reduce air noise inevitable from astandard port. A passive radiator ideally should be capable of very highexcursion and of substantially greater surface area than the activewoofer. A known commercial design with such features uses large woofersand multiple large passive radiators, both of which significantlyincrease the size of the speaker system. Another design uses verycompact enclosures with multiple passive radiators, but these are verylow in efficiency and require very powerful amplifiers to producemeaningful sound pressure level (SPL).

There exists a need to provide a new loudspeaker system to provide highoutput, low distortion, low noise, and extended frequency response.

SUMMARY OF THE INVENTION

According to an exemplary embodiment of the present invention there isprovided a loudspeaker system that includes a speaker enclosure having afirst opening and a second opening; a first speaker manifold mountedwithin the enclosure and including a first back wall, four first sidewalls, and an open first front side substantially in alignment with thefirst opening; a second speaker manifold mounted within the enclosureand including a second back wall, four second side walls, and an opensecond front side substantially in alignment with the second opening; awoofer mounted on a first wall of the first side walls; and an acousticvent mounted in a second wall among the second side walls.

It is to be understood that an “acoustic vent” as used herein refers toa passive radiator, an air port, or other similar device. An acousticvent takes over the output load of a woofer at low frequencies andprovides much of the output. The acoustic vent and enclosure airspacecombine at a certain frequency to resonate, and the woofer drives theresonance. At a range of frequencies around this resonance, the acousticvent moves much more than the woofer.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention can be understood in more detailfrom the following descriptions taken in conjunction with theaccompanying drawings in which:

FIG. 1 illustrates a top cross-section, side cross-section and frontview of a loudspeaker system, respectively according to an exemplaryembodiment of the present invention;

FIG. 2 illustrates a top cross-section, side cross-section and frontview of the loudspeaker system of FIG. 1, respectively where the passiveradiator has been replaced with an air port, according to an exemplaryembodiment of the present invention;

FIG. 3 illustrates a side top section, side cross-section and front viewof a loudspeaker system, respectively according to an exemplaryembodiment of the present invention;

FIG. 4 illustrates a top cross-section, side cross-section and frontview of a loudspeaker system, respectively according to an exemplaryembodiment of the present invention;

FIG. 5 illustrates a top cross-section, side cross-section and frontview of a loudspeaker system, respectively according to an exemplaryembodiment of the present invention;

FIG. 6 is a graph illustrating the output efficiency of the loudspeakersystem illustrated in FIG. 4 as compared to conventional loudspeakersystems;

FIG. 7 is a relative graph of the maximum linear output sound pressurelevel of the loudspeaker system referenced in FIG. 6 as compared toconventional loudspeaker systems;

FIG. 8 illustrates a top cross-section and side cross-section,respectively, of a conventional loudspeaker system having a compactdesign; and

FIG. 9 illustrates a top cross-section and side cross-section,respectively, of a conventional loudspeaker system having a sub-compactdesign.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Exemplary embodiments of the present invention will be described belowin more detail with reference to the accompanying drawings. Thisinvention may, however, be embodied in different forms and should not beconstrued as limited to the embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art.

FIG. 1 illustrates different views of a loudspeaker system, according toan exemplary embodiment of the present invention. Part (a) of FIG. 1illustrates a top cross-section of the present exemplary embodiment.Part (b) of FIG. 1 illustrates a side cross-section of the presentexemplary embodiment. Part (c) of FIG. 1 illustrates a front view of thepresent exemplary embodiment.

Referring to FIG. 1, the loudspeaker system has a speaker enclosure 33which includes a manifold 30, a woofer 31, a passive radiator 32, and apower amplifier 34. The enclosure 33 (also known as a cabinet) is hollowand may be made out of wood, metal or any other suitable material.

The manifold 30 is essentially a well in the enclosure 33 having a pairof substantially parallel side walls, a back wall, a top wall, and abottom wall, forming a manifold chamber. The wall opposite the back wallis substantially open to define a manifold opening.

The woofer 31 is mounted on a first wall of the manifold. The passiveradiator 32 is mounted on a second wall of the manifold 30, such thatthe woofer 31 and the passive radiator 32 face each other at about a 180degree angle or about a 90 degree angle (not shown).

A surround of the woofer 31 may be adjacent to the first wall of themanifold 30 and a surround of the passive radiator 32 may be adjacent tothe second wall of the manifold 30. The surround of the woofer may bepartially covered by the speaker enclosure 33.

The woofer 31 and the passive radiator 32 may be separated from oneanother by a distance which may be determined through experimentation byvarying the dimensions of the manifold. The dimensions of the manifold30 may be optimized to improve low frequency efficiency and distortioncharacteristics, and may vary considerably depending on thewoofer/passive radiator suspension characteristics and desired bandwidthof the system.

The woofer 31 is an active woofer and may be of a conventional highexcursion design. The passive radiator 32 is optionally oval in shape tosave in cabinet volume. The oval design allows for the highest overallsurface area while keeping the total depth of the cabinet to a minimum.It also reduces the overall length of the manifold section, which helpsto prevent any standing wave resonances that may otherwise exit.Embodiments of the present invention, however, are not limited to ovalshaped passive radiators or woofers, as each may be shaped as a circle,a rectangle, a square, or any other suitable shape. The dimensions ofthe passive radiator 32 illustrated in FIG. 1 may be, for example, anoval of ten inches by eight inches. However, the dimensions of thewoofer 31 and passive radiator 32 may vary considerably. Although FIG. 1illustrates using a passive radiator 32 as an acoustic vent, the passiveradiator 32 may be replaced with an air port of suitable length anddiameter. The length and diameter of the air port may be determinedthrough experimentation and adjusted as necessary.

The power amplifier 34 is optionally part of the enclosure 33 since theloudspeaker system may be adapted to use an external power amplifier.The power amplifier may be class A, class AB, class D, class H, or anyother suitable type. The power amplifier may have active electronicsprocessing for equalization, low-pass and high-pass crossovers andoutput limiters to prevent woofer damage or excessive distortion.

FIG. 2 illustrates a different configuration of the loudspeaker systemof FIG. 1, where the passive radiator 32 has been replaced with an airport 43, according to an exemplary embodiment of the present invention.Part (a) of FIG. 2 illustrates a top cross-section of the presentexemplary embodiment. Part (b) of FIG. 2 illustrates a sidecross-section of the present exemplary embodiment. Part (c) of FIG. 2illustrates a front view of the present exemplary embodiment.

Referring to FIG. 2, the loudspeaker system includes an enclosure 42having an air port 43, a woofer 41, a manifold 40, and a power amplifier44. While an opening of the air port 43 is illustrated as facing thewoofer 41 at an angle of about 180 degrees, the woofer may also beadjusted to face the air port 43 at an angle of about 90 degrees (notshown). The air port 43, having a predetermined diameter extends intothe enclosure 42 for a predetermined length. The length and diameter ofthe air port can be determined through experimentation.

FIG. 3 illustrates different views of a loudspeaker system, according toan exemplary embodiment of the present invention. Part (a) of FIG. 3illustrates a top cross-section of the present exemplary embodiment.Part (b) of FIG. 3 illustrates a side cross-section of the presentexemplary embodiment. Part (c) of FIG. 3 illustrates a front view of thepresent exemplary embodiment.

Referring to FIG. 3, the loudspeaker system includes an enclosure 3having a passive radiator manifold 5, a woofer manifold 6, a passiveradiator 2, a woofer 1, and a power amplifier 4. The passive radiatormanifold 5 and the woofer manifold 6 are similar to the manifoldsillustrated in FIGS. 1-2. The structure of the components that make upthis embodiment, such as the passive radiator 2, the woofer 1, andamplifier are similar to those discussed above in FIGS. 1-2.

The passive radiator 2 is mounted to a first side of the passiveradiator manifold 5, such that it faces a second side of the passiveradiator manifold 5 at about a 180 degree angle or about a 90 degreeangle (not shown). The woofer 1 is mounted to a first side of the woofermanifold 6, such that it faces a second side of the woofer manifold 6 atabout a 180 degree angle or about a 90 degree angle (not shown).

A passive radiator manifold opening or exit of the passive radiatormanifold 5 may be on the same side of the enclosure 3 as an exit of thewoofer manifold 6 or may optionally exit on a different surface.

The passive radiator 2 may be a predetermined distance away from oneside of the enclosure 3 based on the size of the passive radiatormanifold 5. The woofer 1 may be a predetermined distance away from aside of the enclosure 3 based on the size of the woofer manifold 6.These distances can be determined through experimentation by varying thedimensions of the passive radiator manifold 5 and the woofer manifold 6as discussed in connection with the manifold 30 illustrated in FIG. 1above.

A surround of the passive radiator 2 may be adjacent to a side of thepassive radiator manifold 5. A surround of the woofer may be adjacent toa side of the woofer manifold. The surround of the woofer may bepartially covered by the enclosure 3.

As discussed above for FIG. 1, the power amplifier is optional and thepassive radiator 2 may be replaced with an air port.

FIG. 4 illustrates a loudspeaker system, according to an exemplaryembodiment of the present invention. Part (a) of FIG. 4 illustrates atop cross-section of the present exemplary embodiment. Part (b) of FIG.4 illustrates a side cross-section of the present exemplary embodiment.Part (c) of FIG. 4 illustrates a front view of the present exemplaryembodiment.

Referring to FIG. 4, the loudspeaker system includes an enclosure 13,having a woofer 11, a first passive radiator 12, a second passiveradiator 14, and a manifold 10. The manifold 10 is similar to themanifolds illustrated in FIGS. 1-3. The structure of the components thatmake up this embodiment, such as the passive radiators 12 and 14, andthe woofer 11 are similar to those discussed above in FIGS. 1-3.

The first passive radiator 12 faces towards the second passive radiator14 at an angle of about 180 degrees. The distance between the firstpassive radiator 12 and the second passive radiator 14 depends on thedimensions of the manifold 10 and can be adjusted throughexperimentation. The woofer 11 is arranged at about a 90 degree anglewith respect to the first passive radiator 12 and the second passiveradiator 14.

A surround of the first passive radiator 12 may be adjacent to a firstside of the manifold 10. A surround of the second passive radiator 14may be adjacent to a second side of the manifold 10. A surround of thewoofer 11 may be adjacent to a third side of the manifold. The woofersurround may be partially covered by the walls of the manifold withoutill effect. In some instances, the entire surround and a portion of thecone may be shaded by the enclosure construction, in a similar manner tocompression phase plugs in high-frequency horn transducers. This servesto improve the coupling efficiency in addition to the gains frommanifolding.

As in the previous embodiments, the power amplifier is optional and thepassive radiators 12 and 14 may be replaced with an air port.

FIG. 5 illustrates a loudspeaker system, according to an exemplaryembodiment of the present invention. Part (a) of FIG. 5 illustrates atop cross-section of the present exemplary embodiment. Part (b) of FIG.5 illustrates a side cross-section of the present exemplary embodiment.Part (c) of FIG. 5 illustrates a front view of the present exemplaryembodiment.

Referring to FIG. 5, the loudspeaker system has an enclosure 25 whichhas a first passive radiator 23, a second passive radiator 24, passiveradiator manifold 22, a woofer 21, a woofer manifold 20, and a poweramplifier 26. The passive radiator manifold 22 and the woofer manifold20 are similar to the manifolds illustrated in the previous figures. Thestructure of the components that make up this embodiment, such as thepassive radiators 23 and 24, the woofer 21, and the amplifier 26 aresimilar to those discussed in the previous figures.

The first passive radiator 23 faces towards the second passive radiator24 at an angle of about 180 degrees or about 90 degrees (not shown). Thefirst passive radiator 23 and the second passive radiator 24 are mountedrespectively to a first and second wall of the passive radiator manifold22. A surround of the first passive radiator 23 may be adjacent to afirst side of the passive radiator manifold. A surround of the secondpassive radiator 24 may be adjacent to a second side of the passiveradiator manifold. A surround of the woofer 21 may be adjacent to a sideof the woofer manifold 20. The surround of the woofer 21 may bepartially covered by the enclosure 25.

As in the previous figures, the power amplifier 26 is optional and eachof the passive radiators 23 and 24 may be replaced with an air port.

It should be noted that while all of the previously discussedembodiments have been illustrated with one or two manifolds, the presentinvention is not limited to any particular number of manifolds. As anexample, a third manifold could be added to the loudspeaker systemillustrated in FIG. 5. Additionally, passive radiators, air ports, andwoofers, could be mounted to sides of the third manifold.

In operation, the interaction of an enclosure having a woofer, a passiveradiator, and a manifold vary based on frequency. At upper frequencies,substantially above the resonant frequency of a enclosure/passiveradiator combination, the woofer cone is loaded in a small chamber,which provides an improvement in the actual air displacement, andprovides actual acoustic output. The cone can get a smaller volume ofair moving easier than making the air in an entire living room. Thisshows up as an acoustic resistance that acts against the cone'sexcursion. Design of the passive radiators is very important at theseupper frequencies because if the passive radiators move much, they willabsorb some of the acoustic output of the active woofer. This is becausethe improved efficiency of coupling the woofer to the manifold's airalso means that the air is efficiently coupled to the front of thepassive radiators. At frequencies just above to just below the enclosureresonance, the internal resonance of the enclosure is very effective atcontrolling the cone motion. At frequencies below the resonance, themanifold provides an acoustic resistance that is not seen inconventional enclosures. The acoustic resistance of the manifold tendsto limit the maximum motion of the cones, which keeps distortion downand helps the mechanical reliability of the components.

FIG. 6 is a graph illustrating the output efficiency of an embodiment ofthe loudspeaker system illustrated in FIG. 4 as compared to aconventional compact loudspeaker system illustrated in FIG. 8, and aconventional sub-compact loudspeaker system illustrated in FIG. 9. Part(a) of FIG. 8 and part (b) of FIG. 8 illustrate a top cross-section andside cross-section, respectively, of a conventional compact loudspeakersystem. The compact loud speaker system includes a passive radiator 52,a woofer 51, an enclosure 53, and a power amplifier 53. FIG. 9illustrates a top cross-section and side cross-section, respectively, ofa conventional sub-compact loudspeaker system. The sub-compactloudspeaker system includes a passive radiator 62, a woofer 61, anenclosure 63, and a power amplifier 64.

Referring to FIGS. 6, 8, and 9, the output efficiency of a conventionalloudspeaker system having a compact design with a round ten inchdiameter passive radiator 52 is illustrated by a dotted curve, theoutput efficiency of a conventional loudspeaker system having asub-compact design with a round ten inch diameter passive radiator 62 isillustrated by a dashed curve, and the output efficiency of anembodiment of the loudspeaker system illustrated in FIG. 4 having twooval ten inch by eight inch passive radiators is illustrated by thesolid curve. As shown in FIG. 6, the embodiment of the present inventionillustrated outperforms the conventional designs by several dB,particularly over the 20 to 100 Hz frequency range.

FIG. 7 is a relative graph of the maximum linear output sound pressurelevel of the embodiment of the loudspeaker system referenced in FIG. 6as compared to the conventional loudspeaker systems of FIG. 8, and FIG.9.

Referring to FIG. 7, the curve of the conventional compact loudspeakersystem having a round ten inch diameter passive radiator 52 is markedwith diamonds, the curve of the conventional subcompact loudspeakersystem having a round ten inch diameter passive radiator 62 is markedwith squares, and the manifolded dual oval ten inch by eight inchpassive radiator embodiment is marked with Xs. The manifolded designgenerally outperforms the conventional designs between the pictured 20and 125 Hz range. Between 25 and 50 Hz, the manifolded designoutperforms the conventional designs by at least 2-3 dB and at somefrequencies by as much as 4-6 dB.

Although the illustrative embodiments have been described herein withreference to the accompanying drawings, it is to be understood that thepresent invention is not limited to those precise embodiments, and thatvarious other changes and modifications may be affected therein by oneof ordinary skill in the related art without departing from the scope orspirit of the invention. All such changes and modifications are intendedto be included within the scope of the invention as defined by theappended claims.

What is claimed is:
 1. A loudspeaker system, comprising: a speakerenclosure having a first opening and a second opening; a first speakermanifold mounted within the enclosure and including a first back wall,four first side walls, and an open first front side substantially inalignment with the first opening; a second speaker manifold mountedwithin the enclosure and including a second back wall, four second sidewalls, and an open second front side substantially in alignment with thesecond opening; a woofer mounted on a first wall of the first sidewalls; and an air port mounted in a second wall among the second sidewalls.
 2. The loudspeaker system of claim 1, wherein the first wallfaces the second wall.
 3. The loudspeaker system of claim 2, furthercomprising a passive radiator mounted within a third wall among thesecond side walls that faces the second wall.
 4. The loudspeaker systemof claim 2, further comprising a second air port mounted within a thirdwall among the second side walls that faces the second wall.
 5. Theloudspeaker system of claim 1, wherein a surround of the woofer ispartially covered by the speaker enclosure.
 6. The loudspeaker system asrecited in claim 1, wherein the speaker enclosure further includes apower amplifier.
 7. The loudspeaker system as recited in claim 1,wherein the first opening and the second opening are on a same side ofthe speaker enclosure.
 8. The loudspeaker system as recited in claim 1,wherein the first opening and the second opening are on different sidesof the speaker enclosure.
 9. The loudspeaker system as recited in claim1, wherein the speaker enclosure is hollow.
 10. The loudspeaker systemof claim 1, where each speaker manifold has a substantially rectangularshape.
 11. A loudspeaker system, comprising: a speaker enclosure havinga first opening and a second opening; a first speaker manifold mountedwithin the enclosure and including a first back wall, four first sidewalls, and an open first front side substantially in alignment with thefirst opening; a second speaker manifold mounted within the enclosureand including a second back wall, four second side walls, and an opensecond front side substantially in alignment with the second opening; awoofer mounted on a first wall of the first side walls; and a passiveradiator mounted in a second wall among the second side walls.
 12. Theloudspeaker system of claim 11, wherein the first wall faces the secondwall.
 13. The loudspeaker system of claim 12, further comprising asecond passive radiator mounted within a third wall among the secondside walls that faces the second wall.
 14. The loudspeaker system ofclaim 12, further comprising a first air port mounted within a thirdwall among the second side walls that faces the second wall.
 15. Theloudspeaker system of claim 11, wherein a surround of the woofer ispartially covered by the speaker enclosure.
 16. The loudspeaker systemas recited in claim 11, wherein the speaker enclosure further includes apower amplifier.
 17. The loudspeaker system as recited in claim 11,wherein the first opening and the second opening are on a same side ofthe speaker enclosure.
 18. The loudspeaker system as recited in claim11, wherein the first opening and the second opening are on differentsides of the speaker enclosure.
 19. The loudspeaker system as recited inclaim 11, wherein the speaker enclosure is hollow.
 20. The loudspeakersystem of claim 11, where each speaker manifold has a substantiallyrectangular shape.